The effect of surface coating and artificial aging on the surface roughness and microhardness of glass ionomer-based restorative materials in- vitro

Yıldırım Y. 2023. The Effect of Surface Coating and Artificial Aging on the Surface Roughness and Microhardness of Glass Ionomer-Based Restorative Materials In- Vitro. Yeditepe University Institute of Health Sciences, Ph.D. Thesis, Istanbul. Glass Ionomer Cements (GIC), due to their chemical bonding to dental tissues with minimal preparation and their fluoride-releasing properties, have become popular in pediatric dentistry. Until the secondary hardening of restorations made using GIC is completed, surface coatings are applied to the restoration surface to reduce its negative physical properties. When applied to glass ionomer restorations, surface coatings improve the properties of materials, such as surface roughness and microhardness. A bioactive restorative material ACTIVATM kids BioACTIVE-RESTORATIVETM (PULPDENT®, Watertown, USA), high-viscosity glass ionomer cement materials EQUIA® Forte Fil (GC Corporation, Tokyo, Japan) and ChemFil® Rock (Dentsply Sirona, Konstanz, Germany) were used within the scope of the study. EQUIA ForteTM Coat (GC Corporation, Tokyo, Japan) was used as a surface coating agent. Thirty-four samples were prepared from each material group, and Equia Forte Coat was applied to half of them. Plexiglass molds (10±0.1 mm in diameter and 2±0.1 mm in depth) were used for surface roughness and microhardness tests. Before and after the thermal cycling procedure, surface roughness and microhardness measurements were performed for all samples. Statistical Package for the Social Sciences (SPSS) 24.0 program was used for statistical analysis. Significance was evaluated at p<0.01 and p<0.05 levels. In the intragroup comparison where the effect of the surface coating application was evaluated, the surface roughness values of all tested materials showed a statistically significant decrease (p<0.05). Surface roughness values in all other tested materials showed a statistically significant decrease after artificial aging (p<0.05). In the intragroup comparison where the effect of the surface coating application was evaluated, the surface hardness value of all tested materials showed a statistically significant decrease (p<0.05). The microhardness value of all other tested materials showed a statistically significant decrease after artificial aging (p<0.05). Keywords: Surface roughness, surface microhardness, thermal aging, glass ionomer cement, artificial aging, in vitro, surface coating.